Do you need two car subwoofers?

Car subwoofers are easily one of the best ways to upgrade a factory audio system in your car. One of the questions we get asked a lot is “do 2 car subwoofers sound better than one”, and it’s an interesting question. The answer will depend on your own personal tastes, budget, and showmanship.

In this guide, we will be exploring the difference between using one subwoofer and two subwoofers in an attempt to help you decide on what is best for your system.

What are your goals for your sound system?

An important question I like to ask at the top of many of my sound articles is “what are you looking to achieve?” because this determines a lot about your buying decision. When looking to put in a second subwoofer, you should have already maximized the capabilities of one subwoofer in your vehicle. This includes having a decent subwoofer, a decent subwoofer enclosure, and a decent amplifier, all compatible and working together to the maximum of their capabilities.

Does having 2 subwoofers double the sound output?

No, having 2 subwoofers does not double the amount of sound being produced. The amount of sound output is counter-intuitive from this reasoning.

It is important to understand that sound output is measured in decibels, which is not a linear scale. Sound output is logarithmic. Let’s say we have a subwoofer currently outputting 100db, which is pretty loud. If you wanted these subwoofers to sound twice as loud, you will need to be producing 110db. Every 10db change sounds twice as loud.

More information is available in this video:

Do you have space for 2 subwoofers?

One of the most important factors to consider when installing a subwoofer or two subwoofers is the amount of free air space you are willing to give the subwoofers.

Many of the subwoofers we recommend come with prefabricated enclosures that will work best with that designated subwoofer. If you do not have a prefabricated enclosure on your subwoofer, you will need to look into space fabrication.

One subwoofer with adequate air space will sound way better than two subwoofers with inadequate air space, so you will need to consider that when deciding to upgrade to multiple subwoofers, and you should only do so if you are willing to provide adequate space to both.

An alternative you can try if you are looking for subwoofers that do not require a lot of space is a shallow mount subwoofer. We put together a review and buying guide on shallow mount subwoofers that you might want to check out.

Will your current amplifier work with two subwoofers?

If you are planning on using your current amplifier on both subwoofers, you will need to make sure that the amplifier will provide both subwoofers with adequate power to function. If you do not provide both subwoofers sufficient power, you might not receive the intended results from the subwoofers.

If you have a monoblock amp that you are wiring to two subwoofers, there are two things to keep in mind, Wattage and Resistance (Ohms)

Wattage

Your amplifier will have a wattage RMS figure per channel. When you connect these two subwoofers up to 1 mono block amplifier, you are dividing the wattage per subwoofer in half. For example, if you have two subwoofers rated at 50 watts each, you should get a mono block amplifier rated at 100 watts for best results.

Resistance (Ohms)

Resistance/impedance can be tricky to calculate correctly because subwoofers can have different resistance figures. We recommend that less advanced installers go for a pair of subwoofers that is identical, as this will provide complementary sound and will make wiring much easier.

The math for calculating resistance isn’t too hard when the subwoofers have the same resistance. For a simple wire diagram and calculation, we recommend this tool by Rockford Fosgate.

Subwoofer Resistance in series circuits: add up the resistance of all components.

Subwoofer Resistance in parallel circuits with the same resistance: Total resistance = (resistance of one subwoofer) / (number of total subwoofers).